In a multimedia conferencing system comprising one or more steerable video cameras and microphones, the relative positions and orientation of the video and audio components must be known in advance of a call in order to initialize the system. Specifically, the location of sources of directional information such as microphone(s) and microphone array(s) relative to camera(s) must be established prior to a video conference call to ensure proper steering of the camera(s) by the talker location signal(s) output from the microphone(s), microphone array(s), etc.
In the past, the location of the camera(s) relative to the microphone array(s) has been rigid and tightly controlled, in order to facilitate the calibration process. More particularly, in the past, microphones and cameras have been mounted on walls and ceilings to provide a known, consistent relative positioning of microphone(s) and camera(s). This type of rigid setup is undesirable where portability of some components (e.g. camera(s)) is required or in small offices where space is at a premium.
Several prior art references disclose the use of fixed location video cameras, microphones and/or microphone arrays, as follows:    K. Wilson, T. Darrell, “Audio-video array source localization for intelligent environments”, Proceedings of IEEE ICASSP, 2002;    Zhang, Z., “A flexible new technique for camera calibration”, Pattern Analysis and Machine Intelligence, IEEE Transactions on, Volume: 22 Issue: 11, November 2000 Page(s): 1330-1334;    Heikkila, J.; Silven, O., “A four-step camera calibration procedure with implicit image correction”. Computer Vision and Pattern Recognition, 1997. Proceedings., 1997 IEEE Computer Society Conference on, 1997 Page(s): 1106-1112; and    Lo D., “Biaxial strain study of porcine aortic valve using stereographic technique.” Faculty of Graduate Studies, University of Western Ontario, London, Ont. 1994.